An actuator, as an element of a product, is mainly applied to equipment such as a sofa, a medical bed, and so on. An existing actuator generally comprises a motor, a worm gear formed as a transmission with the motor, a housing covering around the motor and the worm gear, a spindle with one end fixed in the worm gear, a slide guide sheathed around the spindle and a slide guide fastener and a front cover mounted at two ends of the slide guide respectively, wherein the slide guide fastener is limited on an inner wall of the housing in order to fix the slide guide and the spindle. When the actuator is applied to products with different types or different models, the shape of the actuator will be different because the products are different. Common differences exist in the length of the slide guide, the shape of the slide guide and the configuration of the housing. The slide guide of the actuator is generally made of metal material, and the length of the slide guide can be controlled by a cutting process or a mould. The housing is generally made by plastic injection molding, the configuration thereof can be changed by changing the size of an injection mould or by changing a punch. The whole slide guide should be replaced if the shape of the slide guide needs to be changed. If the slide guide is replaced, the slide guide fastener and the front cover of the slide guide provided at two ends thereof should be also replaced; changing the shape of the slide guide fastener further needs to replace the housing, however, the housing is usually more complex than the slide guide fastener in structure. If there are slide guides with various specifications, they need to match with a variety of slide guide fasteners, and a variety of housings are further needed to match the slide guide fasteners; as a result, the product will have too many components and moulds, such that the cost is high and the producing process is inconvenient.